Field of the Invention
The present invention relates to a transmission for a walk-behind wheeled vehicle, and the present invention also relates to a wheeled vehicle equipped with such a transmission.
The invention relates more particularly to a transmission for a walk-behind wheeled vehicle, the transmission being of the type including at least one preferably non-rotary casing at least partially housing a driver member, such as an inlet shaft, equipped with rotary drive motor means, a rotary driven member, such as a toothed wheel, continuously engaging with the motor driver member, wheel drive means for driving both wheels of a single pair of wheels of the vehicle, said wheel drive means comprising a wheel drive shaft made in one piece or made up of at least two wheel drive shaft segments in alignment, each of which is suitable for driving a respective wheel of the single pair of wheels of the vehicle, and a clutch mechanism disposed between the wheel drive shaft or each of the wheel drive shaft segments and the driven member, the or each clutch mechanism being activated by the driven member being driven in rotation in a “forwards” first rotary drive direction, and deactivatable by the wheel drive shaft or the wheel drive shaft segment with which it co-operates being driven in rotation forwards, when the speed of rotation of the wheel drive shaft or of the wheel drive shaft segment is greater than the speed of rotation of the driven member, the wheel drive shaft or each wheel drive shaft segment being free to turn in either of its directions of rotation when the corresponding clutch mechanism is in the deactivated state.
Description of Related Art
Such transmissions incorporate an “automatic” clutch that, in order to operate, does not need any dedicated control member, such as a fork, as is necessary in conventional clutches.
In such a transmission, while the driven member is being driven in rotation in a “forwards” direction, the clutch mechanism is deactivated when the speed of rotation of the wheel drive shaft is greater than the speed of rotation of the driven member.
Due to the inertia of the vehicle, that characteristic generally enables the clutch mechanisms to be deactivated automatically when the vehicle is stopped.
When the vehicle is stopped, the driven member ceases to turn and the wheel drive shaft or the wheel drive shaft segments for driving the wheels of the vehicle being entrained by the inertia of the vehicle causes the clutch mechanism to be deactivated, then making it easy for the vehicle to be moved over the ground, forwards or backwards.
However, such conditions are not satisfied when the vehicle stops suddenly or on a gradient.
Under such circumstances, the clutch mechanisms remain activated and it is difficult or indeed impossible to move the vehicle backwards by wheeling it over the ground. The driver then needs to have the instinctive reaction of moving the vehicle forwards until the drive means are deactivated so as then to be able to wheel the vehicle backwards.
In addition, and until now, the coupling between the drive outlet shaft of the motor means and the driven member has been voluminous.